water containers

[GoesStation]

So it's five-gallon jug and jerry can ​then.

Only in American English. I doubt the metric world calls those big bottles five-gallon jugs, especially since they only hold four Imperial gallons. (Only the United States used US gallons in the pre-metric days.) Somehow nineteen-liter jug sounds impossibly awkward.

 

[SoothingDave]

"19 liter jug" sounds awfully converted. Like saying your car has 43.18 cm wheels.

 

[GoesStation]

"19 liter jug" sounds awfully converted.

But it states the jug's capacity correctly. You couldn't call it a 20-liter jug because it won't hold that much. I have a hunch that jugs that size are indeed described in European catalogs as 19-liter ones if they're offered there.